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Abstract:

The effect of capillary pressure related to immiscible WAG (Water Alternate Gas) is studied
by use of a numerical simulator. The capillary pressure is found to have a significant effect on
the pressure gradient and the total oil production both in two-phase and three-phase flow
situations. When the capillary pressure is included in the simulation the total oil production is
considerably lower than when the capillary pressure is neglected. Experimentally measured
two-phase capillary pressure was used as input to the numerical simulator. The two-phase
capillary pressure was further used to estimate three-phase flow, related to WAG processes.
A network model was applied to generate a consistent set of two-phase and three-phase
capillary pressure. The network model was anchored to measured two-phase data, and threephase
capillary pressure was constructed. The gas-oil and mercury capillary pressure
anchored the pore structure parameters, while water-oil capillary pressure anchors the
wettability parameters in the network model.
The network model quantifies the difference between three-phase and two-phase capillary
pressure, and in the cases studied the difference between two-phase and three-phase capillary
pressure was significant.